A folding device can be built in several form factors. It can be a clamshell device that flips open into a phone-like device, or it can be a phone-like device that opens into a tablet. Some manufacturers use multiple displays in a clamshell for their foldable. However, this is more of the halfway point to true foldables, which have folding displays.
Rumors indicate that Apple has already begun testing these two folding types, comparable to the Samsung Galaxy Fold (horizontal fold) and the Samsung Galaxy Flip (vertical fold). Both passed the initial tests, but rumors say Apple has decided to move forward with the "flip" style.
Tests are being conducted using OLED and micro-LED, though it is unknown which will fit Apple's final design and supply requirements.
If there is an external display, it will likely inherit the always-on mode found in iPhone 14 Pro. The display dims but doesn't turn off — showing the time, widgets, and other data.
Cameras and Biometrics
Apple tends to put multiple cameras in its most premium devices, and the trend will likely continue for the "iPhone Fold." A standard device has only a front and a back to house cameras, but a folding device has a front, back, outside, and inside to consider.